1. Technical Field
This invention is related to an antenna formed on a printed circuit board which mounts a transmission circuit and/or a reception circuit of an apparatus such as a portable telephone and a transceiver for wireless communicating information, in which information is transmitted from the apparatus via the antenna, and/or information is received by the apparatus via the antenna.
2. Description of the Prior Art
Since portable telephones are rapidly popularized in recent years, needs of wireless information communication apparatus are considerably increased, and also, various sorts of wireless (mobile) information communication services are considered by which these wireless information communication apparatus may be presently made compact and in low cost, and also new markets may be established. On the other hand, desires (needs) as to users who perform wireless information communications are how these users can utilize such wireless information communications in lower cost, easier manners, while securing high reliability as well as high security.
Various technical aspects should be considered in conventional wireless information communication apparatus operable under severe communication environments caused by strong variations, and also in conventional portable communication terminals its apparatus size should be made compact so as to improve portabilities thereof.
As one of key technologies related to the above-explained considering aspects, there are antennas. An antenna is an apparatus which is employed so as to radiate transmission output (power) derived from a transmission-sided apparatus to aerial space as electromagnetic waves, or in order to receive electromagnetic waves from the aerial space as an input to a reception-sided apparatus. Normally, antennas may be operated in similar manners even in any case of transmission antennas and reception antennas, namely these antennas may have a reversible characteristic. However, since electric power levels handled by antennas during reception are extremely low, as compared with electric power levels handled by these antennas during transmission, these antennas may be separately constituted with respect to transmission sides and reception sides.
In general, sleeve antennas and helical antennas are employed as antennas used in wireless (radio) information communication apparatus. As a specially-designed antenna, a slim type antenna (plane antenna) and the like may be also provided. While this slim type antenna is provided on a dielectric board and the like, a thickness of this slim type antenna is made thinner than, or equal to several [cm], namely not-appeal structure, and also, this slim type antenna is mainly utilized in such frequency ranges higher than, or equal to the UHF frequency range (300 [MHz] to 3 [GHz]). Among these antennas, there is an antenna that may be made compact in such a manner that since one end of this antenna is grounded via a capacitor and the like, a length xe2x80x9cLxe2x80x9d of this antenna is made equal to a xc2xc of a wavelength xe2x80x9cxcexxe2x80x9d to be handled (L=xcex/4).
However, in case that an antenna used in a mobile wireless communication was an antenna such as a sleeve antenna which was arranged at an external portion of a mobile wireless communication apparatus, there was a problem. That is, when this sleeve antenna was touched, the antenna characteristic was easily and adversely influenced by a change in directivity and a phenomenon such as a body effect. Also, in the conventional slim type antenna, when a metal piece and the like were located in the vicinity of this slim type antenna, there was such a problem that an antenna characteristic of this slim type antenna was changed. Namely, reflections of transmission outputs from this slim type antenna were increased. Furthermore, in conventional wireless information communication apparatus having portability, the size of the antenna relative to the size of the wireless information communication apparatus is large. There is a need for above-described antennas that can clear the standards as to antenna performance, and also are made compact.
This invention has been made to solve the above-explained problems, and therefore, has an object to provide an antenna capable of being mounted on a compact wireless information communication apparatus and being operated under stable condition without being influenced by a change of directivity and a phenomenon such as a body effect.
To achieve the above-explained object, an antenna of this invention is featured by such an antenna used in a frequency range defined from 700 [MHz] to 3 [GHz] wherein: the antenna is formed on a printed circuit board as an electric conducting pattern having a length of xc2xc (xcex/4)xc2x120 [%] of a wavelength xcex, where the printed circuit board mounts thereon a transmission circuit used in the frequency range; and a portion of the antenna, which is longer than, or equal to ⅔ of an entire length of the antenna, owns a width wider than, or equal to xcex/400.
To achieve the above-explained object, an antenna of this invention is featured by such an antenna used in a frequency range defined from 700 [MHz] to 3 [GHz] wherein: the antenna is formed on a printed circuit board as an electric conducting pattern having a length of xc2xc (xcex/4)xc2x120 [%] of a wavelength xcex, where the printed circuit board mounts thereon a reception circuit used in the frequency range; and a portion of the antenna, which is longer than, or equal to ⅔ of an entire length of the antenna, owns a width wider than, or equal to xcex/400.
The antenna of this invention is formed as the electric conducting pattern on the printed circuit board which mounts the transmission circuit and/or the reception circuit. As a consequence, the antenna space of this antenna can be made smaller than the conventional antenna space, and a total manufacturing stage of this antenna can be reduced. Further, an antenna operable under stable condition can be provided, and also, the size of the apparatus on which this antenna is mounted can be made compact.
In an antenna according to a preferred embodiment mode of the present invention, the portion of the above-described antenna longer than, or equal to ⅔ of the entire length thereof is separated from either a ground portion formed on the printed circuit board or the above-described transmission circuit, longer than, or equal to xcex/400. The above-described antenna is formed as an electric conducting pattern on the printed circuit board which mounts thereon the transmission circuit, while being separated by said distance of at least xcex/400. Also, while transmission output terminal portions are provided on the antenna and the ground portion, the transmission output terminal portion are capable of measuring a transmission output from the transmission circuit, and the antenna is further comprised of a switching portion for switching as to whether or not the antenna is electrically conducted to the transmission circuit.
In an antenna according to a preferred embodiment mode of the present invention, the portion of the above-described antenna longer than, or equal to ⅔ of the entire length thereof is separated from either a ground portion formed on the printed circuit board or the above-described reception circuit, longer than, or equal to xcex/800. The above-described antenna is formed as an electric conducting pattern on the printed circuit board which mounts thereon the reception circuit, while being separated by said distance of at least xcex/800. Also, while reception input terminal portions are provided on the antenna and the ground portion, the reception input terminal portions are capable of inputting a reception signal into the reception circuit, and also, the antenna is further comprised of a switching portion for switching as to whether or not the antenna is electrically conducted to the reception circuit.